Generally, a transient phenomena, where a current higher than a normal current flows just after power is supplied to a power distributing circuit or an electrical device, occurs, and the transient phenomena is referred to as an inrush current. A hot load current that occurs in the first step of an inrush current occurs at the same time with supplying power, and an amount of the hot load current is several times greater than, or tens times greater than, that of normal current. The hot load current causes deterioration of a quality of the electronic product as well as deterioration of a power distributing device, performance degradation of a power distributing device and protection coordination inability. The hot load current occurring in the first step of the inrush current includes an initial inrush current occurring just after being applied to a line, a magnetizing current in a device, such as a motor of a transformer or the like, having a core, a current for increasing a temperature of an incandescent lamp, etc. intensity of the hot load current is tens times greater than that of a normal current, but a continuous time of the hot load current is very short, such as a several Hz. To decrease an electrical shock of an inrush current impacting on electronic products, negative temperature coefficient thermistor (NTC thermistor) or the like is used, but NTC thermistor cannot perform a function of radiating heat. Also, if heat is not radiated, the NTC thermistor cannot perform an original function, and in this case, because heat is diffused to an ambient space, a space in which other semiconductor components are disposed, is heated, and thus, an embeded environment may be deteriorated.
Generally, in use of electronic products such as home appliances, office machines, industrial machines or the like, it is well known that an energy consumption for standby power is significant. For example, in the case of KOREA, it is well known that an energy consumption for standby power is almost 11% of a total energy consumption in a household each year. If this is expanded to 1.5 million households, energy corresponding to 5.2 trillion won is consumed for standby power each year.
The most effective method for preventing the standby power is to separate a portion (a plug), through which power is inputted from the outside, from electronic products, and that is, the method is to pull the plug out of the socket. However, this method make a user inconvenient, and thus, the method is invalid. Also, a method of using various types of auto or manual multi-outlet power strip including a contact switch is provided; but, in this case, when power is to supplied, switches in the multi-outlet power strip and the electronic products have to be doubly operated.
Korean Patent Registration No 10-0945213 titled “APPARATUS FOR CUTTING OFF STANDBY POWER AND METHOD FOR CONTROLLING THEREOF” discloses an apparatus for cutting off standby power including a knob switch, a first switching unit, a second switching unit and a control unit. In the related art, when electronic products turn on, an electrical shock or a spark with an inrush current occurs in the electronic products. That is, the related art impacts electrical quality according to an over current and a change of a voltage value by an inrush current when the electronic products turn on, and thus, the electronic products may be impacted or may be broken.
FIG. 1 is an exemplary diagram showing a time-current characteristic curve for describing an inrush current.
Referring to FIG. 1, an inrush current tens times greater than a normal current for charging a capacitor occurs when an electronic product turns on. If the inrush current is not controlled or is not prevented, a current demand in a line rapidly changes on a very larger scale than an operation current of root mean square RMS. An excessive current may damage devices, electrical elements and electronic components, such as a fuse, solder joint or the like, or may transform them, and may have various bad influences on them.
Moreover, an asymmetric voltage transferred to a control circuit or various components through a power supply may be a cause of generating a breakdown in main components. A Switching Mode Power Supply SMPS, which is mainly used as a power supply among power supplies converting an alternating current AC to a direct current DC applied to various devices, such as computers, communication devices, home appliances, or the like, has a delay time (for example, 0.5 sec) during a switching process of converting an alternating current to a direct current, and generates a noise and electromagnetic waves.
To solve the limitation in the above-described related art, a present invention is provided based on understanding the inrush current and the power supply.